The present invention is generally related to the field of analysis of a medical image, and, more particularly, is related to a system and method for analyzing a magnetic resonance image of stenosis in blood vessels.
Atherosclerosis, the primary cause of heart attack and stroke, is currently responsible for most of the deaths in the Western world. In the United States alone, five million people seek treatment for cardiovascular ailments every year. Several symptoms indicate the need for surgical intervention to alleviate atherosclerotic disease. Some examples of these symptoms are transient ischemic attacks, physical performance on a treadmill stress test, and the existence of a prior incident of artery blockage or narrowing. A particular quantity that has been extensively studied and correlated to the proper clinical treatment is the degree of artery narrowing that is called the xe2x80x9cpercent stenosisxe2x80x9d.
Stenoses limit blood flow by raising the resistance to flow through the vessel. For example, the consequence of the stenosis in the cerebral circulation, where there is otherwise little resistance to flow, is that a significant stenosis can reduce the flow to the brain through that artery. In severe stenosis, a negative transmural pressure may be generated via the Bernoulli effect. If this occurs cyclically with the pulse, a stenosis may suddenly fracture because of mechanical fatigue failure which results in free floating particles in the blood flow which may block subsequent lesser blood vessels and result in stroke or other similar occlusive occurrence.
Consistent with hemodynamics studies such as the North American Symptomatic Carotid Endartectomy Trial, clinical observations indicate that patients with stenosis of approximately 60% or greater are candidates for surgery to correct the blockage. Generally, there is significant risk in the surgical methods which is balanced against the risk of having an atherosclerotic event. Accurate quantification of the percent stenosis is therefore critical in maximizing the patient""s outcome and in minimizing healthcare costs.
The task of quantifying the severity of atherosclerotic narrowing of blood vessels or percent stenosis is called angiography, which refers to the imaging blood vessels. The current most effective method of angiography employed to determine the percent stenosis is x-ray angiography. In x-ray angiography, a catheter is used to deliver a contrast agent to an upstream location of the stenosis. While the contrast agent is released into the blood flow upstream of the stenosis, x-rays are taken of the stenosis and surrounding area. The contrast agent ensures that the outlines of the blood flow are revealed on the x-ray which indicates any narrowing of the blood vessel in question.
However, x-ray angiography has significant drawbacks. For example, the contrast agent is toxic to the kidneys and some patients can develop an allergic reaction. Also, merely catheterizing a patient may cause a stroke or heart attack. Additionally, complications may arise because the catheter insertion point into the artery can heal slowly which necessitates an overnight stay in the hospital overnight for observation, thereby incurring the associated costs.
Another prospective angiographic method employs magnetic resonance imaging (MRI) technology to generate a view of the region containing stenosis of a blood vessel. However, the images generated using MRI generally suffer from inaccuracies due to the movement of blood through the blood vessel and other reasons. Consequently, the precise percent stenosis is very difficult if not impossible to quantify in a given image and MRI angiography is not practical.
The present invention provides a system and method for determining a severity of a stenosis in a blood vessel depicted in a magnetic resonance imaging (MRI) data set. Briefly described, in architecture, the system comprises a neural network configured to calculate the severity of the stenosis in the blood vessel based upon a number of input parameters, and the input parameters including at least one characteristic of a signal void associated with the stenosis in the MRI data set.
The present invention can also be viewed as a method for determining a severity of a stenosis in a blood vessel depicted in a magnetic resonance imaging (MRI) data set. In this regard, the method can be broadly summarized by the following steps: identifying a number of input parameters, the input parameters including at least one characteristic of a signal void associated with the stenosis in the MRI data set, and calculating the severity of the stenosis in the blood vessel based upon the input parameters.
The present invention has numerous advantages, one of which is that the present invention allows the easy and cost efficient determination of a percent stenosis in a patient without invasive and high risk surgical procedures. Other advantages of the invention include the fact that it is simple in design, user friendly, robust and reliable in operation, efficient in operation, and easily implemented for mass commercial production.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention.